In the fabrication of fluid flow systems, whether they be for the purposes of conveying liquid such as petrochemicals, or gases such as natural gas, or even fluidized cereals as is common in the cereal processing industry, the use of conduits or pipes is common and replete. From a fabrication point of view, pipes can only be manufactured to a finite length and therefore, various lengths or elbows must be connected together in order to structure the conduit fluid conveyance means. This is accomplished by welding butt ends of pipes together or to elbows etc., or alternatively, to weld the end of a pipe to a butt flange and to juxtapose two butt flanges together by means commonly known, for example, use of bolts through each juxtaposed annular portions of each butt flange. Generally, such flanges co-operatively employ gaskets as sealing elements.
It is increasingly desired to have these welds tested for the purposes of determining whether there is any leakage. Particularly, in the petrochemical industry, it is now being mandated that the amount of fluid evaporating or escaping from any weld or flange/flange interface be reduced to allowable limits which, up to now, have been about 2 liters per annum to less than a 1/4 of a liter per annum per flange/flange or weld interface. When one considers that in petrochemical plants there are thousands of such welds or butt flanges, the task of testing each of them becomes onerous and costly.